/**
 * OSAmI: Open Source Ambient Intelligence
 * Copyright (C) 2010 Bull S.A.S.
 * Contact: osami-general@osami-commons.org
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307
 * USA
 */

package org.osami.gateway.display.internal;

import java.io.IOException;
import java.io.PrintWriter;
import java.util.Date;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.felix.ipojo.annotations.Component;
import org.apache.felix.ipojo.annotations.Instantiate;
import org.apache.felix.ipojo.annotations.Invalidate;
import org.apache.felix.ipojo.annotations.Requires;
import org.apache.felix.ipojo.annotations.Validate;
import org.osami.gateway.alarm.IAlarm;
import org.osami.gateway.storage.IAlarmStorage;
import org.osgi.service.http.HttpContext;
import org.osgi.service.http.HttpService;
import org.osgi.service.http.NamespaceException;

@Component
@Instantiate
public class DisplayAlarmsServlet extends HttpServlet {

    /**
     * serial version UID.
     */
    private static final long serialVersionUID = -9035540141367237767L;

    @Requires
    private IAlarmStorage storage;

    @Requires
    private HttpContext context;

    @Requires
    private HttpService httpService;

    @Validate
    public void start() throws ServletException, NamespaceException {
        this.httpService.registerServlet(Constants.DEFAULT_DISPLAY_ALIAS, this, null, this.context);
    }

    @Invalidate
    public void stop() {
        this.httpService.unregister(Constants.DEFAULT_DISPLAY_ALIAS);
    }

    private void doGetPost(final HttpServletRequest req,
            final HttpServletResponse resp) throws ServletException,
            IOException {
        PrintWriter writer = resp.getWriter();

        writer.println("<html lang=\"en\">");

        // HTML Head
        // ---------------------------------------------------
        writer.println("<head>");
        writer.println("<title>Active alarms at " + new Date() + "</title>");
        writer.println("<link href=\"/resource/css/designSensor.css\" rel=\"stylesheet\" type=\"text/css\" />");
        writer.println("</head>");

        // HTML Body
        // ---------------------------------------------------
        writer.println("<body>");

        printPageTitle(writer);
        printDisengageForm(writer);

        writer.println("<hr/>\n<a href=\"" + ServletPaths.INDEX + "\">Go back to main page</a>\n");
        writer.println("</body>");

        writer.println("</html>");
    }

    @Override
    protected void doGet(final HttpServletRequest req,
            final HttpServletResponse resp) throws ServletException,
            IOException {
        doGetPost(req, resp);
    }

    @Override
    protected void doPost(final HttpServletRequest req,
            final HttpServletResponse resp) throws ServletException,
            IOException {
        doGetPost(req, resp);
    }

    private void printPageTitle(PrintWriter writer) {
        writer.println("<h1>Active Alarms</h1><hr/>");
    }

    private void printDisengageForm(PrintWriter writer) {
        writer.println("<form action='" + Constants.DEFAULT_DISENGAGE_ALIAS
                + "' method='POST'>");
        printAlarmTable(writer);
        printRightAligned(writer, "<input type='submit' value='Disengage' />");
        writer.println("</form>");
    }

    private void printRightAligned(PrintWriter writer, String content) {
        writer.println("<div style='text-align:right;'>");
        writer.println(content);
        writer.println("</div>");
    }

    private void printAlarmTable(PrintWriter writer) {
        writer.println("<table width='100%' cellpadding='0'>");
        // Print table headers
        writer.println("<thead><tr>");
        // Print each column name here
        printAlarmTableHeaders(writer);
        writer.println("</tr></thead>");

        // Print table body
        writer.println("<tbody>");
        // Print each alarm in its own row
        synchronized(this.storage) {
            for (IAlarm alarm : this.storage) {
                printAlarmRow(writer, alarm);
            }
        }
        writer.println("</tbody>");
        writer.println("</table>");
    }

    private void printAlarmTableHeaders(PrintWriter writer) {
        writer.println("<th>Identifier</th>");
        writer.println("<th>Severity</th>");
        writer.println("<th>Message</th>");
        writer.println("<th>Date</th>");
        writer.println("<th>Disengage</th>");
    }

    private void printAlarmRow(PrintWriter writer, IAlarm alarm) {
        writer.println("<tr>");
        printTableCell(writer, alarm.getIdentifier());
        printTableCell(writer, alarm.getSeverity().name());
        printTableCell(writer, alarm.getMessage());
        printTableCell(writer, alarm.getDate().toString());
        printTableCell(writer, inputCheckbox(alarm));
        writer.println("</tr>");
    }

    private String inputCheckbox(IAlarm alarm) {
        return "<input type='checkbox' name='" + Constants.DISENGAGED_ALARM
                + "' value='" + alarm.getIdentifier() + "' />";
    }

    private void printTableCell(PrintWriter writer, String content) {
        writer.println("<td>" + content + "</td>");
    }

}
